Heart valve (HV) replacements of diseased cardiac valves by prostheses are common and often lifesaving for patients with significant valvular lesions, stenosis, or regurgitation. Depending on the severity of the condition, HV replacement is an expensive yet critical procedure used to restore proper valve function with an increasing number of replacements each year. For example, in 2012 over 290,000 HV procedures were performed worldwide. That number is estimated to triple to over 850,000 by 2050. Thus, the demand for artificial HVs is expanding at a rate of 10-12% per year. With changing demographics and lifestyle choices, demand for a more durable and biocompatible prosthesis is rising. Factors supporting the need to increase research efforts on HV replacements include, but are not limited to, an increasing United States population over the age of 65 years old, an increasing life expectancy and an increasing occurrence of valvular heart disease.
Mechanical heart valves, which have no biologic component, are thrombogenic, causing thrombus formation and thromboemboli. For this reason, anticoagulation must be robust for mechanical HVs. Bioprosthetic heart valves, made from fixed porcine aortic leaflets or bovine pericardium do not have long-term thrombogenicity problems in patients without other risk factors, but have a shorter lifespan due to poor fatigue characteristics used on the natural tissues. HV replacements are frequently revised due to this tendency for mechanical heart valves to form thrombus and bioprosthetic heart valves lack of durability. The need for improved biomaterials in HV therapy has recently intensified with the advent of minimally invasive approaches, which presently use bioprosthetic HVs in a deployable stent or frame, but suffer from the same drawbacks that plague traditional bioprosthetic HVs. Thus, there is a need to increase the longevity and reduce thrombogenicity of HVs and to reduce the number of revision surgeries performed each year. In particular, an improved hemocompatibility of polymeric heart valve leaflets is needed, which is easy and inexpensive to produce and to surgically implement. Also there is a need for HVs engineered specifically for future minimally invasive HV configuration, and for small-diameter vascular grafts that do not suffer from poor patency due to intimal hyperplasia, and thrombus formation.